Quick answer
To fix a sink mixer, turn off the water supply, disassemble the mixer, replace worn seals or cartridges, and reassemble. Check for leaks after turning the water back on.
Confirm the symptom
- Water leaks from the mixer base or handle
- Mixer handle is loose or wobbles
- Water drips continuously from the spout
- Mixer doesn't shut off completely
- Cold and hot water mix unexpectedly
Tools and prep
- Adjustable wrench
- Screwdrivers (flathead and Phillips)
- Plumber's tape
- Replacement cartridges or seals
- Bucket or towel to catch water
- Turn off water supply under the sink
- Protective gloves and safety glasses
Step-by-step troubleshooting
- Turn Off Water SupplyDo: Locate and turn off the shut-off valves under the sink.Observe: Water stops flowing from the mixer.Means: Water supply is safely cut off.Next: Disassemble the mixer
- Disassemble the MixerDo: Use screwdrivers to remove the handle and expose the cartridge or valve.Observe: Handle and cartridge are accessible.Means: You can now inspect internal components.Next: Inspect for damage
- Inspect for DamageDo: Check the cartridge, seals, and O-rings for wear or cracks.Observe: Visible damage or wear on parts.Means: Identify which parts need replacement.Next: Replace faulty parts
- Replace Faulty PartsDo: Install new cartridges, seals, or O-rings as needed.Observe: Parts fit snugly and securely.Means: Leakage and mixing issues should be resolved.Next: Reassemble the mixer
- Reassemble the MixerDo: Put the handle and other components back in place.Observe: Mixer is fully reassembled.Means: Prepares the mixer for testing.Next: Test the mixer
- Test the MixerDo: Turn the water supply back on and check for leaks.Observe: No leaks and water temperature is consistent.Means: Repair was successful.Next: Final check
Common causes
| Cause | Likelihood | Difficulty | Part often needed |
|---|---|---|---|
| Worn O-rings or seals Over time, rubber parts degrade and lose their seal. | Common | Easy | O-rings, seals |
| Faulty cartridge Cartridges can wear out, causing leaks or improper mixing. | Common | Easy–Medium | Cartridge |
| Loose handle or valve Handles can become loose due to regular use. | Sometimes | Easy | Handle screws |
| Corroded valve seat Mineral buildup can damage the valve seat over time. | Sometimes | Medium | Valve seat |
| Incorrect installation Improper assembly can lead to leaks or malfunction. | Rare | Easy | Plumber's tape |
| Blocked aerator Mineral deposits can clog the aerator, affecting water flow. | Sometimes | Easy | Aerator |
Parts matching
Match your sink mixer issue to the right part:
- Replace O-rings and seals for leaks around the base
- Install a new cartridge for mixing issues or continuous dripping
- Tighten handle screws for a wobbly handle
- Use plumber's tape on threads to prevent leaks
- Clean or replace the aerator for poor water flow
Check the manufacturer’s model number for exact part compatibility.
When to call a professional
- Persistent leaks after replacement
- Complex internal damage beyond basic repair
- Uncertain about identifying the correct parts
- No shut-off valves under the sink
- Multiple fixtures with similar issues indicating a larger problem
FAQ
How do I know if my mixer uses a cartridge or a valve?
Check the model number or look for a square or round slot under the handle—cartridges often have a square slot for removal tools.
Can I fix a mixer without turning off the water?
No—always turn off the water supply to avoid flooding and ensure safety.
Why does my mixer leak after I fix it?
Improper installation, missing O-rings, or damaged parts can cause post-repair leaks. Double-check all connections and seals.
How often should I replace mixer parts?
O-rings and seals every 2–5 years; cartridges every 5–10 years, depending on usage and water quality.
What if I don’t see shut-off valves under the sink?
Turn off the main water supply to the house before proceeding with repairs.